THE LITHIUM ABUNDANCE IN EXTREME HALO STARS

High-dispersion echelle spectra which include the Li I lambda-6708 line are reported for six extremely metal poor dwarfs with T(e) greater-than-or-equal-to 5950 K and -2.89 less-than-or-equal-to [Fe/H] less-than-or-equal-to -2.59. The resulting lithium abundances for these six stars span the range 1.99 less-than-or-equal-to N(Li) less-than-or-equal-to 2.24, where N(Li) = 12 + log (Li/H). Within the observational uncertainties, these results agree with each other and with the abundances reported previously for five other metal-poor dwarfs with [Fe/H] less-than-or-equal-to -2.60. The invariance of the lithium abundance in these 11 stars which show a wide range of very low metallicities and of Galactic orbits favors a primordial origin for most or all of the lithium observed in these oldest Galactic stars.